Gas Turbine Vane Cooling Structure With Offset Posts
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Solution Overview
Problem
The cooling performance of gas turbine vanes is degraded due to obstruction between the gap flow and impinging jet, and thermal expansion causes non-uniformity in the distance between the sidewall and insert, leading to inefficient cooling.
Innovation Solution
The introduction of posts between the sidewall and insert, arranged in rows with offset insert holes, disperses the gap flow and reduces obstruction by directing the impinging jet and gap flow to prevent cross-flow phenomena, maintaining uniform distance and enhancing cooling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling fluid is discharged through film holes in the sidewall, then film cooling is achieved, but gap flow obstruction occurs between the insert and sidewall
Solution Approach 1:
Posts are introduced as intermediary elements between the insert and sidewall to mediate the interaction between gap flow and impinging jet. The posts prevent direct obstruction while maintaining the cooling function, acting as a buffer that redirects flows constructively
Solution Approach 2:
The gap flow path is segmented by the posts into multiple sub-paths. Instead of a single obstructed flow path, the posts create multiple smaller channels that allow cooling fluid to pass through more effectively, reducing the harmful obstruction effect
2Temperature
If the insert is positioned close to the sidewall for effective cooling, then cooling efficiency improves, but thermal expansion causes non-uniform distance and degrades cooling performance
Solution Approach 1:
The posts change the geometric parameters of the gap between insert and sidewall by providing a reference surface. This maintains a controlled, uniform distance that accommodates thermal expansion while preserving cooling effectiveness
Solution Approach 2:
The posts are pre-positioned on the insert surface to establish the correct gap geometry before thermal expansion occurs. This preliminary positioning ensures that even when thermal expansion happens, the uniform distance relationship is maintained
3Temperature
If multiple rows of insert holes are arranged in parallel, then cooling coverage increases, but cross-flow obstruction occurs between adjacent rows
Solution Approach 1:
The posts are positioned asymmetrically relative to the insert holes, creating an offset pattern that breaks the symmetry of cross-flow paths. This asymmetric arrangement prevents direct confrontation between adjacent row flows, reducing cross-flow obstruction
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration effectively reduces obstruction and maintains uniform cooling performance even at high temperatures, improving the overall cooling efficiency of the gas turbine vane.
Implementation Method 1
The cooling fluid, particularly cooling air, passing through the insert 50 is referred to as an impinging jet 14, and the cooling action to cool the vane by contact of the impinging jet 14 with the sidewall 20 of the vane is referred to as impingement cooling
Implementation Method 2
the flows 11, 12, and 13 in which the impinging jet 14 is discharged from the vane through the film holes of the sidewall 20 to cool the sidewall 20. The cooling by the flows is referred to as film cooling
Implementation Method 3
the insert is thermally expanded due to an increase in temperature of air in the insert according to the operation of the gas turbine, thereby causing non-uniformity in the distance between the sidewall 20 and the inner surface 22
Data Source
AI summary
A gas turbine vane includes a sidewall having a plurality of film holes formed therein and defining an airfoil having a leading edge and a trailing edge, a cut-back formed at the trailing edge of the airfoil defined by the sidewall, an insert spaced apart from an inner surface of the sidewall and installed within the sidewall while having a plurality of insert holes formed therein, and a plurality of posts extending from the sidewall. The plurality of insert holes are formed in a plurality of rows, the insert holes of each row are arranged at a distance from the leading edge to the trailing edge, and a surface of the insert is positioned on the posts.